Tay-Sachs disease

Tay-Sachs disease, inherited disorder that occurs primarily in Jewish people from eastern Europe. Children born with the disease have little or no active hexosaminidase enzyme, the lack of which causes fat to accumulate in the brain's ganglions (bundles of nerves). The consequences are mental retardation, paralysis, blindness, and cherry-red spots on the retina of the eye. The disorder is usually fatal before the child reaches the age of four.